MUNICH — US Defense Secretary Chuck Hagel called on European allies to invest more strategically in military projects, particularly as NATO’s mission in Afghanistan comes to an end and many nations reduce defense spending.

Speaking at the Munich Security Conference, formerly called Wehrkunde, Hagel said the US military is looking for allies to pick up missions as the Pentagon downsizes after more than 12 years at war.

“We’re developing strategies to address global threats as we build more joint capacity with European militaries,” Hagel said Saturday.

“In the face of budget constraints here on the continent, as well as in the United States, we must all invest more strategically to protect military capability and readiness,” he said. “The question is not just how much we spend, but how we spend together.”

One way the Defense Department plans to outline its future plans is through the Quadrennial Defense Review (QDR), a document that sets military priorities and strategy. Hagel gave some insight into the QDR, which will be released in the coming months.

The US defense secretary said the strategy document would place an emphasis on working with allies. These allies — who have increased their own expertise through more than a decade of war — could play a valuable role in training and assisting less-capable militaries.

“There are some capabilities that the United States military will continue to invest heavily in,” a senior defense official said. “His expectation is that we will continue to be the world leader in those kinds of capabilities.”

Among those capabilities are the nuclear and missile defense missions, the senior official said.

“Despite fiscal constraints, the budget that we will release next month fully protects our investment in European missile defense,” Hagel said in his speech.

The US is implementing a multiphased missile defense plan in Europe that includes the installation of interceptors in Poland. Missile defense was one of the most discussed items when Hagel visited Poland earlier this week.

Hagel said US partnerships with the UK and Australian militaries could offer “a model for closer integration with other allies and partners — including NATO as a whole — and will influence US strategic planning and future investments.”

The US is helping the UK regenerate its aircraft carrier capability and an Australian is deputy commanding general of US Army forces in the Pacific.

“The Department of Defense will work closely with our allies’ different and individual strengths and capabilities, from the training of indigenous forces to more advanced combat missions,” Hagel said.

In his 11 months as defense secretary, Hagel said he has worked closely with his former senate colleague, Secretary of State John Kerry, to restore “balance to the relationship between American defense and diplomacy.”

After a more than a decade on a “war footing,” Hagel believes “the nation’s foreign policy should and rightly be led by the State Department with the Defense Department in full support,” the senior defense official said.

“The secretary firmly believes in that concept, that foreign policy had become too militarized over the last decade or so and that it’s time for us to be a supporting role when it comes to the execution of this country’s foreign policy,” the official said.

Hagel’s speech took a far different tone than former Defense Secretary Robert Gates took in 2011 when he sharply criticized European allies for not adequately funding their own defense programs.

Hagel said his comments were similar to Gates, just delivered differently.

“Partnerships mean partnership,” Hagel said afterward during a question-and-answer session. “Everybody has to participate, everyone has to contribute, everybody has a role to play.”

Kerry, in his address to the conference, said, “turning inward is not an option” and allies should contribute to assistance programs.

“Leading does not mean meeting in Munich for good discussions,” Kerry said. “It means committing resources, even in a difficult time, to make certain that we are helping countries to fight back against the complex, vexing challenges of our day.”

Hagel in his speech also noted that China and Russia “are rapidly modernizing their militaries and global defense industries, challenging our technological edge and defense partnerships around the world.”

The comments were similar to ones made by Pentagon acquisition chief Frank Kendall, who has recently said he was concerned that spending cuts in research-and-development could erode the US military’s technological superiority.